Extracting the photoproduction cross sections off the neutron, via the γn→π-
p reaction, from deuteron data with final-state interaction effects
The incoherent pion photoproduction reaction γd→π -pp is considered theoretically in a wide energy region E th≤Eγ≤2700 MeV. The model applied contains the impulse approximation as well as the NN and πN final-state-interaction (FSI) amplitudes. The aim of the paper is to study a reliable way for getting the information on elementary γn→π-p reaction cross sections beyond the impulse approximation for γd→π-pp. For the elementary γN→πN, NN→NN, and πN→πN amplitudes, the results of The George Washington University (GW) Data Analysis Center (DAC) are used. There are no additional theoretical constraints. The calculated cross sections dσ/dΩ(γd→π-pp) are compared with existing data. The procedure used to extract information on the differential cross section dσ/dΩ(γn→π -p) on the neutron from the deuteron data using the FSI correction factor R is discussed. The calculations for R versus π-p center-of-mass (CM) angle θ1 of the outgoing pion are performed at different photon-beam energies with kinematic cuts for a "quasifree" process γn→π-p. The results show a sizable FSI effect R≠1 from the S-wave part of pp-FSI at small angles close to θ1∼0: this region narrows as the photon energy increases. At larger angles, the effect is small (|R-1| 1) and agrees with estimations of FSI in the Glauber approach. © 2011 American Physical Society.
Tarasov, VE; Briscoe, WJ; Gao, H; Kudryavtsev, AE; Strakovsky, II
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